mm: make read_cache_page synchronous

Ensure pages are uptodate after returning from read_cache_page, which allows
us to cut out most of the filesystem-internal PageUptodate calls.

I didn't have a great look down the call chains, but this appears to fixes 7
possible use-before uptodate in hfs, 2 in hfsplus, 1 in jfs, a few in
ecryptfs, 1 in jffs2, and a possible cleared data overwritten with readpage in
block2mtd.  All depending on whether the filler is async and/or can return
with a !uptodate page.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 0 insertions, 6 deletions

diff --git a/fs/nfs/symlink.c b/fs/nfs/symlink.c
index f4a0548..bc28213 100644
--- a/fs/nfs/symlink.c
+++ b/fs/nfs/symlink.c
@@ -61,15 +61,9 @@ static void *nfs_follow_link(struct dentry *dentry, struct nameidata *nd)
 		err = page;
 		goto read_failed;
 	}
-	if (!PageUptodate(page)) {
-		err = ERR_PTR(-EIO);
-		goto getlink_read_error;
-	}
 	nd_set_link(nd, kmap(page));
 	return page;
 
-getlink_read_error:
-	page_cache_release(page);
 read_failed:
 	nd_set_link(nd, err);
 	return NULL;